Assembly method for overload protector means



April 28, 1964 B. J. PLElSS, JR 3,130,479

ASSEMBLY METHOD FOR OVERLOAD PROTECTOR MEANS Filed March 6, 1961 2 Sheets-Shet 1 WEDGING INSULATING MATERIAL INTO END TuRNs or sr Ton WINDTNG FORMING A SUBSTANTIALLY V-SHAPED SEGMENT OF INSULATING MATERIAL CONTOURING A HEATSINK AROUND A DUMMY MEANS TO BE POCKETED THEREIN TELESCOPING THE V-SHAPED SEGMENT AND HEAT SINK WITH DUMMY mzANs CURING INSULATING'MATERIAL WITH SEGMENT, HEAT SINK ,AND D MMY MEANS IN PLACE ONLY AFTER CURING 'RENOVE DUMMY MEANS FOR REPLACE" ENT BY ACTUAL OVERLOAD PROTECTOR IN V EN TOR.

BERNARD J. PLEISS JR.

A ril 28, 1964 B. J. PLEISS, JR

ASSEMBLY METHOD FOR OVERLOAD PROTECTOR MEANS Filed March 6, 1961 2 Sheets-Sheet 2 REMOVABLE SEGMENT V-SHAPED INSULATION PIECE m Y u N m L O E A m I L E T 0! TP N w w NWT 5. R N M VM I R U E 5 B FASTENING TIE CORD:

f HIS ATTORNEY United States Patent C) 3,130,,4 ASSEMBLY METHGD FOR OVERLOAD PRUEECTQR MEANS Bernard .9. Pleiss, in, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Mar. 6, 1961, Ser. No. 93,391 1 Claim. (Cl. 29155.5)

This invention relates to procedure for assembly of dynamoelectric machines, and particularly, to provision of an inexpensive overload-protector dummy means replaceable at any time with an actual overload-protector means fully reliable and accessible for servicing.

An object of this invention is to provide an assembly procedure for dynamoe-lectric machines wherein there are steps of putting a depression or pocket-like recess in end turns of a winding fitted with a dummy means to simulate an overload-protector in the depression or recess complementary thereto, setting under heat such as by baking the complementary relationship between insulation and the dummy means, and replacing the dummy means with an actual overload-protector means fully reliable and accessible for servicing free of damage to insulation.

Another object of this invention is to provide a method or" using a forcibly driven dummy means of rigid material such as metal and the like to simulate external shape of an actual overload protector means into a complementary fit with respect to insulation including, for example, curable material such as varnish, epoxy resin and the like to form a pocket around this dummy means for subsequent replacement thereof by an actual overload protector means fully reliable and accessible for servicing though when installed the actual overload protector means is buried yet removable with respect to the insulating material which maintained free of damage for replacement purposes thereby saving cost of expensive new stator assembly as encountered when previously insulation became damaged upon attempted removal of an originally installed actual overload protector that would result in a weak spot susceptible to shorting and breakdown of electrical insulation of the stator windings.

A further object of this invention is to provide a specific improvement in procedure for overload protector mounting in dynamoelectr-ic machine stator winding end turns which have varnish-like insulation relatively thickly added thereto at least locally for forming a pocket complementary to a metal dummy means subjectable to axial driving force for fitting the same into the end turns and replaceable by an actual overload protector means simulated by the dummy means removable without damage to insulation, the actual overload protector means being fully reliable and accessible for servicing regardless of installation by the manufacturer as well as a customer who can optionally add actual overload protector means even if the dummy means was lefit in place upon receipt thereof and subsequent possible future re-use of the same dummy means by the manufacturer of the dynamoelectric machine.

Another object of this invention is to provide a procedure for overload protector mounting in dynamoelectrio machine stator winding end turns subject to steps of wedging a piece of insulating material in a predetermined winding location during formation of end turns, forming a substantially V-shaped segment or portion of insulating material, contouring a substantially V-shaped metal foil around a dummy means to be pocketed therein, telescoping the V-shaped segment and toil with dummy means, substituting and securing the segment and foil as well as the dummy means in place of the piece of insulating material so as to leave the dummy means accessible and replaceable by an actual overload protector means.

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Further objects and advantages will become apparent from the following description, reference being had to the drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 illustrates a portion of dynamoelectric machine structure made accordance with the procedure of the present invention.

FIGURE 2 is a fragmentary cross sectional view taken along line 22 in FIGURE 1.

FIGURE 3 represents a flow chart of procedure in accordance with the present invention.

FIGURE 4 is an exploded perspective view to illustrate procedure as to use of dummy means in an overload protector mounting.

In view of sensitivity and delicate structure including bimetallic contact means having predetermined calibration for operation to protect a dynamoelectric machine, for example, there is danger of damage to such overload protector means While proceeding to manufacture a stator lamination assembly subjected to mechanical jolts or blow as well as high temperatures such as during baking or curing of insulating materials applied thereto. Sometimes a thermostat or overload protector means on a dyn'amoelectric machine stator and coil assembly can be defective or damaged under such manufacturing and assembling conditions and such a fault is not discovered until the assembly has been supplied to a customer. Assurance of proper operation and reliability in such assemblies shipped to customers is a desirable condition and advantage strived for. Procedure for assembly of dy-namoelectric machines in accordance with the present invention is related to a disclosure of a co-pending application =S.N. 93,392 filed concurrently with the present disclosure setting forth in further detail certain advantages including desirability of an inexpensive and practical protector mounting that can provide adequate insulation as well as serviceabili-ty. Procedure in accordance with the present invention makes allowance for marginal requirement of overload protector means by some customers who install actual overload protector means when needed. Thus the manufacturer in following the procedure of the present invention can adapt a dynamoelectric machine to be provided with actual overload protector means without costly modification and rebuilding of a stator assembly including insulated end turns of a stator winding.

In FIGURE 1 there is shown a stator portion or assembly generally indicated by numeral '10 used for dyn-amoelectric machine structure in accordance with the present invention. The stator assembly comprises a group or stack of individual l-aminations 1'1 each having a plurality of radially inwardly extending slots 12 fitted with main windings It as well as phase or auxiliary and starting windings 15. Suitable energizing leads including a common connection 16 as well as a main winding Wire 18 and phase winding wire 19 are provided in the stator assembly 10 for energization of the main winding portions 14 and auxiliary or starting windings 15.

The drawings in FIGURES 1 through 4 serve to illustrate procedure in accordance with the present invention. FIGURES 1 and 2 illustrate end results of procedures in accordance with the present invention, while FIGURES 3 and 4 are representative of steps involved in reaching such a result. As aninitial step there is the provision and wedging of insulating material 20 shown in FIGURE 4 and placement thereof in a predetermined location relative to end turns of one of the elements or portions of the main Winding 14. This insulating material or segment is preferably a rectangular-shape piece of cardboard, resin-impregnated glass cloth, :and the like removable for subsequent steps of the procedure in accordance with the present invention. Next there is the forming of a substantially V-shaped insulation piece or segment of insulating material made of a terephthalate polyester commercially available as Nylar that can be slideably inserted from an apex end thereof along a surface on one side of the removable insulating material or card 26. The V-shaped insulation piece is represented by reference numeral 22 in FIGURES 2 and 4. Another step in accordance with the present invention is that of contouring a heat sink indicated by numeral 24. around a dummy means generally indicated by numeral as in views of FIGURES l, 2 and 4. This dummy means 26 is made of metal such as steel having a generally wedge shaped body portion 27 adapted to telescope in a contour fit relative to a pocket portion 29 of the heat sink 24. The heat sink 24 can be made of a metal foil or bendable and reformable material such as copper adapted to fit inside the pocket portion 2% of the heat sink or foil 24. it is to be understood that there is a step of telescoping the V-shaped insulation piece or segment and heat sink as well as the dummy means for substitution thereof in place of the removal card of insulating material 20.

An important advantage in the use of metal dummy means 26 involves the fact that a suitable mallet, hammer or other tool for pounding the telescoped insulation piece, foil and dummy means into place cannot result in severe shock to a delicate component such as an actual overload protector means. In fact, during a step of forcibly driving the telescoped segment, heat sink and dummy means into location axially in the end turns of the main winding 14 there is a flattened head or end of the housing portion 27 of the dummy means 26 that can be specifically subjected to severe pounding and the wedge shape of the housing portion together with the telescoped V-shapes of the insulation piece and heat sink or foil facilitate the inserting of the telescoped parts in accordance with the present invention.

It is to be noted that dummy means 26 must remain in place in an axial location with respect to the end turns of the main windings so that pocket portion 29 formed during contouring of the heat sink around the dummy means remains intact. As is apparent in FIGURES l and 4, the pocket portion 29 can be located laterally olfset to one side with respect to width of the heat sink or metal foil 24. Thus the pocket portion 29 is located off center within the copper foil heat sink and a subse quently installed actual overload protector means substituted for the dummy means 26 upon removal of the latter can operate with greater reliability and uniformity as to heating due to varying the position of the thermostat means with respect to the end turns of windings such as 14. The pocket portion 29 can be stabilized by fastening such as spot welding on opposite sides of the pocket to prevent variations due to shifting of the winding end turns or dummy means as well as an actual overload protector means. For further details as to positioning of actual overload protector means with respect to such a pocket portion reference can be made to a co-pending application S.N. 93,392 filed concurrently herewith. The actual overload protector means illustrated in this copending application, for example, has terminal means projecting axially from one end thereof and these terminal means can be bent, loosened or otherwise damaged if subjected to forcible driving of telescoped insulation piece 22 and heat sink or foil 24. Subsequent to forcible driving of these telescoped components into end turns of a winding such as 14- there is a fitting of an insulating sleeve 30 having a cutout or slot 31 therein extending laterally to accommodate wires or leads joined to terminals on an actual overload protector means as shown in the copending application. An insulating member 32 having an opening or aperture 33 corresponding to offset positioning of the pocket portion 29 can be fitted over this sleeve 30 and an outer periphery of the end turns of a winding such as 14. Offset positioning of the dummy means 26 is exaggerated in FTGURE 1 though conceivably the pocket portion 29 and aperture 33 could be coincident with each other in any laterally displaced location with respect to the insulation and heat sink or metal foil. A suitable fastening or tie cord 34 can be provided to retain components in place with respect to end turns of a winding such as 14.

Suitable insulating coating such as varnish and the like can be added to the end turns of wiring such as by dipping, spraying and the like followed by a step of curing insulating material such as by baking and heating with the V-shaped insulation piece 22, heat sink such as 24, dummy means 26 as well as other insulating components in place. Only after this curing should the dummy means be removed for replacement by an actual over load protector means. This removing of the dummy means can be accomplished by forcible prying thereof out of the pocket portion 29 leaving a recess or space complementary to wedge-like shape of an overload protector means housing portion such as shown in the copending application identified earlier. The removing of the dummy means can be a step followed by the manufacturer of the dynamo-electric machine as well as by a customer who may choose to install overload protector means when a need or requirement therefor arises. For example, the dynamoelectric machine stator assembly can be shipped from the manufacturer to the customer with the dummy means such as as remaining in place and the dummy means can be removed upon installation of the stator assembly on an appliance such as a compressor for an air conditioner and the like. The dummy means upon being removed is replaced with the actual overload protector means and the dummy means can be returned to the manufacturer for re-use in a subsequently manufactured dynamoelectric machine assembly following the procedure in accordance with the present invention.

It is to be noted that any suitable overload protector means can be used and that in place of a metal foil as a heat sink, it is possible to have a predetermined shape of heat sink cast integrally into place directly with a housing portion of an overload protector means. In such a situation, the dummy means would also be pre-shaped to complement the shape of the actual overload protector means and the same procedure could be followed with respect to formation of a cavity or pocket in insulating material fitted to end turns of a winding such as 14. In either event, the dummy means could be subjected to driving force and pounding which an actual thermostat or overload protector means could not withstand without danger of damage to delicate components thereof. Also, it is to be noted that an actual thermostat or overload protector means could be damaged by heat during baking and with only a dummy means in place during this curing step there is avoided any possibility of further damage to a thermostat or protector means due to any shrinkage or warping of components thereof. Even when heat sink material is cast integrally into place or formed integrally with a housing portion of a dummy means as well as an overload protector means there can be more metal or heat conducting material on one side than on another. Both the dummy means and actual overload protector means can be readily replaced and serviced when the components are assembled following the steps of procedure in accordance with the present invention. It is noted particularly that both the dummy means and actual overload protector means are buried and removable in a pocket portion that assures reliability and success in heat transfer. The method of assembling the parts in accordance with the present invention assures placement as well as serviceability of overload protector means in good heat arnsfer relationship to end turns of a winding such as 14. Provision of a pocket portion such as 29 permits removal of either dummy means or overload protector means free of any damage to insulation with respect to winding end turns and thus there is a considerable saving in cost where previously complete rebuilding would be necessary to repair damage to insulation. Thus, a simple operation of removing an end frame of a dynamoelectric machine and replacing either a dummy means or actual overload protector means can be easily accom plished without costly and lengthy disruption of use of a particular dynamoelectric machine. Quite often if varnish-like insulation was damaged relative to end turns of a winding there would be a weak spot that would sooner or later result in failure or electrical shorting of the dynamoelectric machine installation. There have been probes inserted into end turns of windings of dynamoelectric machine but these have been subject to ambient conditions resulting in inadvertent operation of overload protector means and failure to properly serve the purpose thereof whereas the overload protector means installed in accordance with the present invention and imbedded in a pocket portion such as 29 assures accurate response to heating of the windings themselves and further provides the important advantage of replaceable and serviceable overload protector means without resorting to teardown or rebuilding of a stator assembly. Dependability and ability of the overload protector means to react to Winding temperature can be consider ably enhanced by following the procedure of using a dummy means during assembling of the components and thus avoiding forcible driving impact on the delicate overload protector means. Also the heat of curing or baking need not be applied to the overload protector means. Shape of the heat sink can be modified during casting or stamping as well as contouring thereof to conform to any particular heat exchange characteristics desired between end turns of a particular winding and an overload protector means to be used therewith.

It is to be noted that in place of tie cord or string suitable insulating tape can be used for holding the parts in assembled relationship and that the dummy means 26 as wedged into the pocket portion 29 remains in the pocket during both the varnishing and baking steps and is removed only after completion of the stator assembly for a dynamoelectric machine. A close fit is obtained whereby good heat conduction and consistent operation is obtained in a thermostat or overload protector means which is substantially identical in outer shape to the dummy means such as 26 fitted to the end windings during the curing and baking. The card 2%) of insulating material or cardboard is to remain in place during the forming of end turns but after forming of the end turns the cardboard is removed simultaneously with wedging and installation of the V-shaped piece and foil as well as dummy means 26. Under no circumstances is the dummy means 26 removed from the pocket portion 29 prior to dipping and baking of the stator and coil assembly. Suitable electrical testing for high potential can be accomplished with the dummy means 26 in place.

While this description is directed to a single phase dynamoelectric machine, it is to be understood that embodiments of this invention can also be used for polyphase dynamoelectric machines.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms can be adopted.

What is claimed is as follows:

In a procedure for establishing an overload protector mounting in the end turns of a dynamoelectric machine stator windings, the steps comprising, forcing a wedge into the end turns of the stator winding to form a pocket therein; removing said Wedge; forming a V-shaped segment of sheet insulating material; contouring a metal foil heat sink around a dummy means, said dummy means having the same general shape as an actual overload protector; telescoping the V-shaped segment and the heat sink with said dummy means; forcibly driving the telescoped segment, heat sink and dummy means into the pocket in the end turns; applying an insulating coating to the end turns; curing said coating; and removing said dummy means for replacement by an actual overload protector.

References Cited in the file of this patent UNITED STATES PATENTS 2,471,840 Scely May 31, 1949 FOREIGN PATENTS 177,180 Austria June 15, 1953 577,403 Italy May 31, 1958 

